The invention relates to a video signal recording apparatus and a reproducing apparatus and, more particularly, to a video signal recording apparatus and a reproducing apparatus using a small optical disk as an information recording medium and to an optical disk which is used for such apparatuses.
The recent improvement in the recording density of an optical disk apparatus is remarkable. The recording density of data which can be used by the user per unit area has been improved at a rate of 40% a year. In a DVD (Digital Versatile Disc) system using an optical disk having a diameter of 12 cm, thus, a system such that data of 4.7 GB per side can be recorded as a DVD-ROM (Read Only Memory: the overwriting is impossible), data of 3.9 GB can be likewise recorded as a DVD-R which can be overwritten only once, and further, data of 2.6 GB can be recorded as a DVD-RAM (Random Access Memory: rewritable any time) has been developed.
On the other hand, an image information compressing technique for reducing the amount of information in a motion image with small deterioration in picture quality has also progressed remarkably due to the development of an image processing technique. Particularly, since the MPEG2 image compressing algorithm by the MPEG (Motion Picture Experts Group) has been put into practical use, the recording and reproduction of a motion image of a low rate of 4 to 5 Mbps and an adequate picture quality can be performed.
Thus, the motion image of two or more hours can be recorded into a DVD-ROM of 4.7 GB and a DVD Video player using such a disk has been put on the market.
Since a lengthy motion image time can be recorded on the optical disk as mentioned above, a motion image of time that is sufficient for practical use in an apparatus using an even smaller optical disk can be recorded.